The jointing of optical cables gives rise to many problems. The joints are complicated because each joint must connect all the systems in the cables, e.g. the optical fibres, the tensile elements, and the electrical conductors. This is particularly true of submarine cables which are designed to survive the stringent conditions imposed by a life of 25 years submerged in the sea or ocean.
It is desirable to test joints not only in commercial operations such as manufacturing cables, laying cables and repairing damaged cables but also in research. One test comprises measuring the attenuation of fibres in the joint before and after the joint is stressed with a simulated working load. Faulty jointing technique is shown by increased attenuation t the joint; in extreme instances communication is broken at the joint. In less extreme manifestations the attenuation is acceptable when the joint is first made but the lift of the joint is substantially less than the requirement. The problems of jointing are more severe when it is necessary to joint two cables with different structures.